Determining spin based on club parameters

Abstract

Methods and apparatus for determining spin of a golf ball in flight. At least a portion of an observed trajectory of the golf ball and one or more parameters associated with the trajectory are obtained. The parameters are selected from launch angle, ball speed, club speed and ball carry. Two or more spin candidates are obtained for the golf ball. Each spin candidate has an associated probability. A most probable used golf club for launching the golf ball into the observed trajectory is determined by matching the observed parameters with parameters for two or more different golf clubs. Ball spin probability data are obtained for the most probable used golf club. The spin of the golf ball is the most probable spin candidate, based on the ball spin probability data and the observed trajectory. The determined spin of the golf ball is displayed on a display device.

We claim as our invention the following: 
     
         1 . A computer-implemented method ( 200 ) for determining spin of a golf ball in flight, comprising:
 obtaining, at a spin determination program of a data processing apparatus, at least a portion of an observed trajectory of the golf ball and one or more parameters associated with the observed trajectory, wherein the one or more parameters include one or more of launch angle, ball speed, club speed, ball carry, or a combination thereof, the observed trajectory comprising three-dimensional locations of the golf ball over time, as determined from observations of the golf ball by one or more camera based tracking sensors;   obtaining, at a spin determination program of a data processing apparatus, two or more spin candidates for the golf ball, each spin candidate having an associated measurement probability indicating relative frequency of different spin values;   determining, at a spin determination program of a data processing apparatus, a most probable used golf club for launching the golf ball into the observed trajectory, based on probability data for one or more parameters for two or more different golf clubs;   obtaining, at a spin determination program of a data processing apparatus, ball spin probability data for the most probable used golf club;   determining, at a spin determination program of a data processing apparatus, the spin of the golf ball to be the spin candidate which is most probable, based on the ball spin probability data and the obtained portion of the observed trajectory; wherein the determining is based on a combination of measurement probability, club spin probability and physics probability, wherein the club spin probability indicates how likely the most probable used golf club generated the spin candidate, and the physics probability refers to probability converted from an error between the observed trajectory and a simulated trajectory, and   displaying the determined spin of the golf ball on a display of a user interface device.   
     
     
         2 . The method of  claim 1 , further comprising:
 adjusting the obtained probabilities for the spin candidates based on predetermined parameters of the most probable used golf club and/or based on a similarity between the portion of the observed trajectory and a corresponding portion of the simulated trajectory for the obtained two or more spin candidates; and   determining the spin of the golf ball to be the spin candidate having the highest adjusted probability.   
     
     
         3 . The method of  claim 2 , wherein determining the most probable used golf club comprises:
 for each golf club in the plurality of different golf clubs, comparing the obtained one or more parameters to the probability data for the one or more parameters for the two or more different golf clubs.   
     
     
         4 . The method of  claim 3 , where the probability data is either a Gaussian probability distribution or a measured histogram probability distribution for the two or more different golf clubs. 
     
     
         5 . The method of  claim 2 , wherein determining a most probable used golf club comprises:
 providing the obtained one or more parameters as input to a previously constructed network of nodes with trained weights, which has been trained for the two or more different golf clubs using one or more obtained parameters from earlier golf ball flights.   
     
     
         6 . The method of  claim 2 , wherein the ball spin probability data is defined as a mean spin value and a standard deviation of spin values for the most probable used golf club. 
     
     
         7 . The method of  claim 2 , wherein the similarity between the portion of the observed trajectory and a corresponding portion of a simulated trajectory for a spin candidate is determined by:
 simulating a trajectory of the golf ball having the spin of the spin candidate, wherein the simulation uses a physics model and one or more of the obtained parameters;   selecting a plurality of instances in time; and   for each selected instance, determining a difference between the observed trajectory and the simulated trajectory, respectively, and combining the differences to obtain a similarity value to be used when adjusting the probability for the spin candidate.   
     
     
         8 . The method of  claim 7 , wherein:
 the difference is a difference in one or more of: acceleration, velocity, and/or position of the golf ball, and   combining the differences includes one or more of: averaging the differences, summing the differences, and/or comparing the difference to find the smallest difference.   
     
     
         9 . The method of  claim 7 , further comprising modifying the differences prior to combining the differences by adding a weight factor to each difference and/or raising one or more of the differences to a predetermined power. 
     
     
         10 . The method of  claim 1 , wherein the method is performed at a golf practice range or golf course. 
     
     
         11 . The method of  claim 1 , wherein the one or more sensors include a radar, a camera, or both. 
     
     
         12 . A computer software program product arranged to, when executed, perform the method operations of  claim 1 . 
     
     
         13 . A system for determining spin of a golf ball in flight comprising:
 a data processing apparatus comprising a processor and   a memory, the memory containing instructions that, when executed by the processor, causes the processor to:   obtain at least a portion of an observed trajectory of the golf ball and one or more parameters associated with the observed trajectory, wherein the one or more parameters include one or more of launch angle, ball speed, club speed, ball carry, or a combination thereof, the observed trajectory comprising three-dimensional locations of the golf ball over time, as determined from observations of the golf ball by one or more camera based tracking sensors;   obtain two or more spin candidates for the golf ball, each spin candidate having an associated measurement probability indicating relative frequency of different spin values;   determine a most probable used golf club for launching the golf ball into the observed trajectory, based on probability data for one or more parameters for two or more different golf clubs;   obtain ball spin probability data for the most probable used golf club;   determine the spin of the golf ball to be the spin candidate which is most probable, based on the ball spin probability data and the obtained portion of the observed trajectory, wherein the determining is based on a combination of measurement probability, club spin probability and physics probability, wherein the club spin probability indicates how likely the most probable used golf club generated the spin candidate, and the physics probability refers to probability converted from an error between the observed trajectory and a simulated trajectory; and   display the determined spin of the golf ball on a display device.